The present invention generally relates to sheet metal working, and more particularly to removal of dents from sheet metal surfaces of automobiles, airplanes, recreational vehicles, trailers, boats, house siding and the like.
Sheet metal is widely used as the surface skin on vehicles, enclosures and shelters. Aluminum is conventionally used on airplanes while automobiles normally have sheet steel bodies. Both aluminum and steel are used to form house siding. A protective coating is often applied to the exterior surface of these sheet metal bodies. Sheet metal thickness is relatively thin in these applications to ease forming operations, and to minimize cost and weight. However, relatively thin sheet metal is susceptible to concave denting, frequently from projectiles such as hail, rocks or other small objects impacting the sheet metal surface.
Removing dents can be cost effective versus removing and replacing the damaged sheet metal, particularly if the repair can be accomplished without the necessity for subsequent surface sanding, grinding or refinishing operations. Various dent-removing tools and methods are conventionally known.
One known method is to fill-in the concave indentation with metal or plastic which is subsequently smoothed and refinished to match the adjacent surface. Repair techniques involving fillers are time-consuming, labor-intensive, messy and expensive. If the dent is accessible from behind, the sheet metal forming the dent can be hammered or pushed back out to its original condition. Frequently, the rear of dented panels are often enclosed and access is difficult. So-called xe2x80x9cpaintless dent repairxe2x80x9d methods often involve drilling small access holes into enclosing panels or structures and using specialized hand tools to remotely access the dented surface. This practice requires highly-trained labor, is tedious, expensive and leaves numerous access holes in the enclosing panel or structure.
Consequently, a number of tools have been developed to remove concave dents from the exterior of the dent. Perhaps best known is a slide hammer or xe2x80x9cslapxe2x80x9d hammer with a screw-end. The screw-end is first embedded in a hole drilled into the dent. A pulling force is then applied by rapidly sliding a weight or hammer along a rod away from the screw and against a stop on the end of the rod opposite the screw. Such devices damage the surface being repaired by leaving a screw hole in it which must be subsequently filled and refinished.
Non-destructive means to grasp the dented material have been employed as well, most notably, a conventional suction cup. Vacuum is used to attach a suction cup to the indented material. Subsequently, mechanical means are used to pull the suction cup, and the attached indented material, outward. Levers, chains, slide hammers and hydraulics have been employed to apply the outward force to the suction cup. The suction device often hides the indentation from view making it difficult to bring the sheet metal into precise alignment with the adjacent surfaces. If the indentation has stretched the sheet metal too much, the suction cup force pulls the dent beyond the intended position leaving a convex dimple in the sheet metal surface.
Various conventional electromagnetic means have been used to remove dents from magnetic and non-magnetic metal surfaces. An electromagnet is positioned over the dent and energized with electricity creating a magnetic field. Magnetic sheet metal surfaces can be directly drawn flat against the face of a matrix formed in the shape of the desired surface. A magnetic metal element is used behind a non-magnetic metal surface. The electromagnet draws the magnetic backing material through the non-magnetic surface pinching the non-magnetic surface into the desired shape. Access behind the non-magnetic surface is obviously required. Electromagnetic tools are cumbersome and expensive to construct and operate.
For reasons stated above and for other reasons presented in greater detail in the Description of the Preferred Embodiments section of the present specification, a dent removal system and method is desired which removes dents quickly, simply, accurately and inexpensively.
The present invention is generally directed to a system and method for forming sheet metal. The invention is particularly suited for forming sheet metal, such as to remove dents and the like, quickly, simply, accurately and inexpensively. While the present invention is not necessarily limited to a sheet metal forming application, such as dent removal, the invention will be better appreciated using a discussion of exemplary embodiments in such a context.
In an example embodiment, the present invention provides a system for forming sheet metal including a chamber head for receiving vacuum into its interior and a vacuum inlet valve, arranged between the vacuum chamber head and a vacuum source, for controlling the receipt of vacuum. The vacuum chamber head has a sealing arrangement for providing a substantially airtight seal between the vacuum chamber head and the sheet metal, and an outlet valve for releasing the vacuum from the interior of the vacuum chamber head. The sealing arrangement includes a plurality of gaskets located one within the perimeter of another. The gaskets decrease in depth profile and compressibility from outside gasket to inside gasket. Vacuum is applied to spaces between gasket seals. The sheet metal is formed to the shape of a template internal to the vacuum chamber head. A matrix of standoff pins indicate the sheet metal topography and communicate the form of the template to the sheet metal surface while allowing vacuum to pass therethrough. The standoff pin matrix is visible through a clear window in the vacuum chamber head. The window has crosshairs to indicate the center of the vacuum chamber head and standoff pin matrix. Springs dampen the speed of sheet metal movement caused by vacuum forces. The system further includes a vibrational energy source magnetically coupled to the sheet metal through a thin protective layer in close proximity to the vacuum chamber head, and a shaper vacuum roller to attract and compress the sheet metal surface into a uniform profile.
In another example embodiment, a shaper vacuum roller for forming sheet metal is provided including an enclosed, hollow cylinder adapted on at least one end to receive vacuum. One or more vents are provided through the wall of the cylinder. Vacuum is received by the cylinder and drawn through the vent(s) such that when the shaper vacuum roller is placed in contact with a sheet metal surface, the vacuum through the vents attracts the sheet metal towards the shaper vacuum roller, to which the shaper vacuum roller cylinder wall provides and opposite resisting force acting to compress the sheet metal surface. A housing substantially impedes vacuum from being drawn through cylinder vents not in contact with the sheet metal surface. The cylinder can be adapted to roll within the housing. The vent(s) are shaped in a tapered fashion such that when the cylinder rolls, a narrow portion of the vent lifts up from the surface of the sheet metal first, thus aiding in the release of vacuum pressure at each vent to ease rolling action. In one example embodiment, the vents are substantially diamond-shaped and arranged such that the tips of the diamonds separate (e.g., lift) from the sheet metal first as the cylinder rolls. The housing can be handle-shaped and include a switch for controlling the receipt of vacuum to the shaper vacuum roller.
In yet another aspect of the invention, a method of forming sheet metal using vacuum is provided including positioning a vacuum chamber head having an internal template over the sheet metal surface, sealing the vacuum chamber head to the sheet metal surface, supplying vacuum to the vacuum chamber head to pull the sheet metal surface into the shape of the template, venting and removing the vacuum chamber head. Vibrational energy is provided to the sheet metal prior to supplying vacuum. Springs can be used to dampen the movement speed of the sheet metal surface due to vacuum forces. The sheet metal surface is rolled with a shaper vacuum roller to remove minor surface imperfections.
The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. While dent repair is illustrated, other sheet metal forming operations can benefit from the teachings described herein. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the present specification. The claims are intended to cover such modifications and devices.